CC Sabathia's absence underscores Masahiro Tanaka's value

When the New York Yankees gave Masahiro Tanaka seven years and $155 million, general manager Brian Cashman immediately began to downplay expectations. He famously declared that the Yankees projected Tanaka to be nothing more than a No. 3 starter in his rookie year.

Seven weeks into the pitcher's first season in the United States, it's clear the Yankees need him to be much more than that.

With 60 percent of their rotation on the disabled list, and Opening Day starter CC Sabathia likely to sit out until July because of a degenerative knee issue, 25-year-old Tanaka has become the unquestioned leader of a rotation in shambles. And it's likely to stay that way for a while.

Cashman said on Monday that Sabathia is expected to miss another six weeks after having a stem cell injection late last week.

"Could it be sooner? Yeah," Cashman said. "But I think this is a more likely and accurate scenario."

Cashman said Sabathia has been on crutches since Thursday's injection, but he was expected to get rid of those in a day or two. Sabathia will then begin a rehab process that starts with pool work, followed by a flat-ground throwing program, then bullpens, then a minor-league rehab assignment to get stretched out.

The timetable is a little bit uncertain, but six weeks seems to be the best estimate.

"They don't have any real certain time," Cashman said. "It's somewhat of a new protocol, so they don't have any predictability yet in terms of consistent, it kicks in after X-amount of time. They have conveyed that the longer you can give it, the more effective the procedure."

With Ivan Nova lost for the year because of Tommy John surgery, and Michael Pineda at least two weeks from returning from an upper-back injury, the Yankees already have converted two relievers into starters and called up a rookie starter from Triple-A.

Cashman said he's scoured the trade market, but it's hard to find a match this early in the season. And giving the slew of pitching injuries throughout baseball, supply is low and demand is high. It's not a buyer's market.

"If you could force something externally, we would have done that already," Cashman said.

Converting late-inning setup man Adam Warren into a starter remains a possibility if the Yankees need additional rotation help this season. Warren has pitched well as a late-inning fireman, but he was a minor-league starter and could be moved back into the rotation if necessary.

Cashman said he'd prefer not to lose a valuable bullpen arm, but the rotation is running out of alternatives.

"That's something we may very well have to do at some point," Cashman said.

For now, it's Tanaka and a bunch of uncertainty. Hiroki Kuroda hasn't been nearly as reliable as he was the past two years, David Phelps and Vidal Nuno have been inconsistent since moving from the bullpen to the rotation, and rookie Chase Whitley has made just 15 starts in his professional career.

Tanaka, 6-0 with a 2.17 ERA, has pitched more like an ace than a No. 3, and the Yankees need that to continue. With Sabathia signed for another two years with a vesting option for 2017, this might not be the only season when Tanaka is asked to pick up the slack.

"We're going to have to wait and play it out," Cashman said. "Whether you're worried about things or not, it's not going to change what it is."

Jennings writes for the (Westchester County, Ny.Y.) Journal News, a Gannett affiliate